Stable vegetation and environmental conditions during the Last Glacial Maximum: New results from Lake Kotokel (Lake Baikal region, southern Siberia, Russia)

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Quaternary International xxx (2013) 1e11

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Stable vegetation and environmental conditions during the LastGlacial Maximum: New results from Lake Kotokel (Lake Baikal region,southern Siberia, Russia)

Stefanie Müller a,*, Pavel E. Tarasov a, Philipp Hoelzmann b, Elena V. Bezrukova c,d,Annette Kossler a, Sergey K. Krivonogov e

a Institute of Geological Sciences, Palaeontology, Freie Universität Berlin, Malteserstr. 74-100, Building D, 12249 Berlin, Germanyb Institute of Geographical Sciences, Physical Geography, Freie Universität Berlin, Malteserstr. 74-100, Building B, 12249 Berlin, Germanyc Institute of Archaeology and Ethnography, Siberian Branch of Russian Academy of Sciences, Novosibirsk 630090, RussiadA.P. Vinogradov Institute of Geochemistry, Siberian Branch of Russian Academy of Sciences, Irkutsk 664033, Russiae Institute of Geology and Mineralogy, Siberian Branch of Russian Academy of Sciences, Novosibirsk 630090, Russia

a r t i c l e i n f o

Article history:Available online xxx

* Corresponding author.E-mail address: [email protected] (S. Mülle

1040-6182/$ e see front matter � 2013 Elsevier Ltd ahttp://dx.doi.org/10.1016/j.quaint.2013.12.012

Please cite this article in press as: Müller, Sresults from Lake Kotokel (Lake Baikalj.quaint.2013.12.012

a b s t r a c t

This paper presents a new decadal-resolution fossil pollen record from Lake Kotokel (52�470N, 108�070E,458 m a.s.l.) and provides a reconstruction of the Last Glacial Maximum (LGM) vegetation and environ-ments in the study area during this interval of globally harsh climate. Lake Kotokel is situated close to theeastern shoreline of Lake Baikal, in the boreal forest zone of southern Siberia. The analysed 190 cm longsection 6of the bottomcoreKTK10 (KTK10/6) consists of compact, undisturbed, greenish-grey todark-grey,slightly laminated silty clay indicating continuous lacustrine sedimentation throughout the LGMperiod ca.26.8e19.1 cal. ka BP. The age model is supported by 11 calibrated AMS dates. The results of pollen analysisand pollen-based biome reconstruction show that steppe and tundra vegetation composed of grasses andvarious herbs dominated ca. 26.8e19.1 cal. ka BP. Occurrence of conifer tracheids and stomata throughoutthe record, together with small quantities of boreal conifer and broadleaf tree and shrub taxa pollen,suggests the presence of single trees or small forest stands in the lake vicinity, most likely in the rivervalleys. Application of the biomisation method and the resulting numerical scores of the most character-istic biomes (steppe, tundra and cold deciduous forest) showminor fluctuations, signifying stability of theregional vegetation cover during the analysed LGM interval. In contrast to the regional biomes, the localenvironmental indicators demonstrate greater sensitivity of the lake system to decadal- and century-scaleclimate variability. The highest pollen percentages of Ranunculaceae, representing littoral/meadowvegetation communities, are registered ca. 23.8e23.4 cal. ka BP. This and an increase in coarse-grained sandparticles together with slightly increased total inorganic carbon (TIC) values representing calcite in theKTK10/6 sediment provide evidence of a much shorter than present distance between the coring site andthe shoreline and a reduced lake area, in line with a drier-than-present LGM climate. A general stability ofthe grassland vegetation in the study region ca. 26.8e19.1 cal. ka BP and relatively constant total organiccarbon (TOC) values support the hypothesis that this productive vegetation could stably serve as aperennial food resource for large populations of herbivores, thus providing favourable environments forthe local hunteregatherers inhabiting the Lake Baikal region during the LGM interval.

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1. Introduction

Southern Siberia and the Russian Far East played a key role inoccupation and reoccupation by late Upper Palaeolithic groups inresponse to changing environmental conditions, in particular for

r).

nd INQUA. All rights reserved.

., et al., Stable vegetation anregion, southern Siberia, R

the extreme conditions of the Last Glacial Maximum (LGM)covering the time frame from ca. 26.5 to 19 ka BP (Clark et al.,2009). Published archaeological records (e.g. Okladnikov, 1950,1955, 1959; Weber, 1995; Weber and Katzenberg, 2002;Parzinger, 2006; Weber et al., 2010, 2013; and references therein)and environmental records (Tarasov et al., 2007, 2009; Bezrukovaet al., 2013; White et al., 2013 and references therein) reveal anintriguing human habitation and environmental history in the

d environmental conditions during the Last Glacial Maximum: Newussia), Quaternary International (2013), http://dx.doi.org/10.1016/

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Fig. 1. Schematic maps showing (A) location of the study area in Eurasia; (B) the vicinity of Lake Kotokel near Lake Baikal; and (C) the KTK10 coring site location.

S. Müller et al. / Quaternary International xxx (2013) 1e112

Baikal region during the Holocene. The Holocene humaneenvi-ronmental interactions are the focus of the Baikal-Hokkaido-Archaeology Project (BHAP, http://bhap.artsrn.ualberta.ca/,Tarasov et al., 2013a; Weber et al., 2013) which aims to better un-derstand the long-term patterns of culture change among hunteregatherer populations inhabiting these two representative regions.However, the BHAP only covers the time interval of the past ca.9000 years, whereas the human habitation history of eastern Eur-asia and the Baikal region can be traced back to late Pleistocenetime (e.g. Dolukhanov et al. 2002; Vasil’ev et al., 2002; Metspaluet al., 2006; Lbova, 2009; Svendsen et al., 2010; Buvit and Terry,2011). Though archaeological and geochronological data fromwestern Europe show numerous evidence of human occupationduring the last glacial interval, including Marine Isotope Stages(MIS) 2 and 3 (e.g. Dolukhanov et al., 2002; Conard and Bolus,2008), results of geoarchaeological research covering the Mediter-ranean region suggest severe decline or even total collapse of hu-man populations during the extreme oscillations towards a coldand arid climate, the so-called Heinrich Events (Weniger, 2008).Understanding which role climatic and environmental conditionsplayed in the life of Palaeolithic inhabitants of southern Siberia andthe Baikal region requires high-quality archaeological and palae-oenvironmental data. This work, which is still underway, is payinggreat attention to chronological control and time resolution of thearchaeological and environmental archives.

Lake Kotokel, located on the western shore of Lake Baikal, hasbeen an important object of palaeoenvironmental studies sincetwo sediment cores from the southern lake basin (KTK1 andKTK2) and several cores from the surrounding peat bogsrevealed pronounced changes in vegetation cover and compo-sition and lake-internal bio-productivity, caused by the long-and short-term variations in temperature and atmosphericprecipitation throughout the last glacial and the Holoceneinterval (Bezrukova et al., 2008, 2010; Shichi et al., 2009; Tarasovet al., 2009; Kostrova et al., 2013). The KTK2 sediment coreretrieved in summer 2005 (Shichi et al., 2009) provided pollen,diatom and climate records, yielding a temporal resolution of ca.200e500 years (i.e. 250 years on average) over the last glacialinterval (Bezrukova et al., 2010). As demonstrated by furthergeophysical investigation of the lake (Zhang et al., 2013), theKTK2 core did not penetrate the whole lacustrine sediment

Please cite this article in press as: Müller, S., et al., Stable vegetation anresults from Lake Kotokel (Lake Baikal region, southern Siberia, Rj.quaint.2013.12.012

sequence. Moreover, the lack of material did not allow higherresolution multi-proxy analyses of the KTK2 core and showedthe necessity of obtaining another core from the lake. This taskwas partly accomplished in 2010.

In the current study we present a new pollen record from LakeKotokel, which covers the interval between ca. 26.8 and19.1 cal. ka BP (i.e. the LGM) with an average temporal resolutionof ca. 40 years. Together with other analytical and reconstructionresults from the same core, this pollen record is then used todiscuss the regional environmental dynamics and terrestrialecosystem stability in the study region during the LGM. In a finalstep, results are discussed along with published archaeologicaldata from the Baikal region and compared with publishedcontemporary results of geoarchaeological studies from otherregions of Eurasia.

2. Regional setting

2.1. Site location and coring details

Lake Kotokel (52�470N, 108�070E, 458 m a.s.l.) in southernSiberia (Fig. 1A) is a 15 km long and approximately 6 km widebasinwith awater area of about 69 km2 and a catchment area of ca.183 km2 (Kostrova et al., 2013). The lake is situated only 2 km awayfrom the eastern shore of Lake Baikal (Fig. 1B). The bathymetricmapping performed in May 2011 shows a ca. 4 m mean waterdepth and an almost flat lake bottom (Zhang et al., 2013). AlthoughLake Kotokel has an outflow to Lake Baikal (Fig. 1C) via the riversIstok, Kotochik and Turka (Kostrova et al., 2013 and referencestherein), there is no evidence that Baikal water has penetrated toKotokel during the past ca. 47e50 ka (Shichi et al., 2009;Bezrukova et al., 2010).

The sediment core KTK10 (52�47.2760N, 108�07.4350E) wasretrieved during a coring campaign in July 2010. The Livingston-type piston corer was applied, which allowed subsequent extrac-tion of 190 cm long sediment sections (diameter 7.6 cm) within thecoring depth interval 0e770 cm, and 200 cm long sediment sec-tions (diameter 7 cm) within the coring depth interval 770e1370 cm. The coring site locationwas chosen in the southern part ofthe lake, ca. 1.8 km from the nearest shoreline and only a few me-tres apart from the sites where KTK1 and KTK2 cores were collected


http://bhap.artsrn.ualberta.ca/

S. Müller et al. / Quaternary International xxx (2013) 1e11 3

(Fig. 1C). The sediment stratigraphy indicates that the most suitablecoring sites for palaeoenvironmental studies are located in thesouthern part of the basin, where almost undisturbed sediments upto a depth of ca. 50 m can be expected (Zhang et al., 2013). Therecovered KTK10 core includes a section of the undisturbed LGMsediment (KTK10 Section 6, hereafter named KTK10/6), which hasbeen selected for the purpose of the current study.

2.2. Modern climate and vegetation

The regional climate, including that of the study area, is conti-nental with long, cold winters and short, hot summers (Alpat’evet al., 1976). Near Lake Kotokel, the two meteorological stations ofCheremukhovo and Goryachinsk are situated less than 10 km apart,(Galaziy, 1993; Bezrukova et al., 2013). The averaged station recordsdocument a mean January temperature of �19.4 �C, mean Julytemperature of 14.7 �C, annual precipitation of ca. 375 mm, and ca.176 days with snow cover around Lake Kotokel. The modern pre-cipitation distribution has a well-pronounced summer maximumin July and August. During these months, westerly winds domi-nating through the year become weak, and southeastern cyclones

Table 1Summary of the AMS radiocarbon dates from the KTK10/6 and KTK2 sediment cores of Lake Kotokel (Fig. 2A). Radiocarbon years before present were converted to calendaryears using the CalPal Online Radiocarbon Calibration software (Danzeglocke et al., 2008). All dates were processed in the Pozna�n Radiocarbon Laboratory (Pozna�n, Poland).Samples representing the KTK2 core were published by Bezrukova et al. (2010).

Core name Respective coredepth (cm)

Dated sediment 14C age (years BP;68% range)

Calibrated age (cal. years BP;68% range)

Lab. number

KTK10/6 15e16 Dark-grey silty clay 17,230� 90 20,990e20,400 Poz-40941KTK10/6 35e36 Dark-grey silty clay 17,310� 90 21,070e20,480 Poz-40942KTK10/6 55e56 Dark-grey silty clay 18,410� 100 22,360e21,710 Poz-40944KTK10/6 75e76 Dark-grey silty clay 20,560� 120 24,820e24,230 Poz-40945KTK10/6 105e106 Dark-grey silty clay 20,120� 90 24,360e23,760 Poz-52847KTK10/6 145e146 Dark-grey silty clay 21,780� 110 26,570e25,580 Poz-52848KTK10/6 185e186 Dark-grey silty clay 21,590� 100 26,130e25,290 Poz-52849KTK2 685e689 Blackish silty clay 12,680� 60 15,300e15,080 Poz-27585KTK2 795e799 Grey silty clay 18,000� 90 21,610e21,430 Poz-27586KTK2 918e922 Grey silty clay 21,450� 110 25,710e25,250 Poz-27587KTK2 1036e1040 Grey silty clay 27,820� 200 32,570e32,090 Poz-27589

bring warm andwet Pacific air to the region, causing heavy rainfallsat the eastern branch of the Polar front (Bezrukova et al., 2008). Bycontrast, the precipitation associated with the Atlantic air massesbrought by the westerly winds is not abundant and mainly fallsduring autumn and spring. During winter, dry, cold and sunnyweather often occurs, because of the stationary Siberian Anti-cyclone occupying the area (Tarasov et al., 2009).

Related to these moderately harsh continental climatic con-ditions, modern vegetation of the study area east of Lake Baikalconsists of boreal coniferous and deciduous forests (Galaziy,1993). Forests are mainly composed of Pinus sylvestris (Scotspine), Larix sibirica (Siberian larch) and Betula (birch) trees, withsome admixture of Populus tremula (aspen) and Alnus fruticosa(shrubby alder). Boreal evergreen conifers, including Pinus sibirica(Siberian pine), Abies sibirica (Siberian fir) and Picea obovata (Si-berian spruce), grow on the mountain slopes of Ulan-Burgasy. Atelevations above 1800 m the mountain taiga is replaced by colddeciduous birch and larch forests and shrubby communities withPinus pumila, Alnus fruticosa and Betula middendorfii (Bezrukovaet al., 2010). Alpine tundra occupies large areas north andnortheast of Lake Baikal, whereas steppe vegetation is widespreadon the Baikal’s largest island of Olkhon, northwest of Lake Koto-kel, and in the semiarid depressions along the Selenga River(Fig. 1B).


3. Materials and methods

3.1. Sub-sampling strategy and radiocarbon dating

The KTK10/6 core section (coring depth interval 970e1170 cm;length of the undisturbed core segment 190 cm) was cut into halffor further sub-sampling and lithological description performed inthe Institute of Geochemistry (Irkutsk). One half was cut into 1 cmslices, packed in plastic containers and transported to FU Berlin forstorage and further analyses. Seven bulk sediment samples (1 cmthick slices) were submitted to the Poznan Radiocarbon Laboratory(Poland) for AMS age determination. The sample details and datingresults are summarised in Table 1. All samples were dated usinghumin fraction, i.e. sediment after removal of carbonates (HCltreatment) and humic acids (NaOH treatment). For comparisonwith the earlier studies of the KTK1 and KTK2 cores (Tarasov et al.,2009; Bezrukova et al., 2010) all radiocarbon dates were calibratedusing the online version of CalPal-2007 calibration software andthe CalPal-2007-Hulu calibration curve (Danzeglocke et al., 2008;Weninger et al., 2013). All ages are expressed in cal. ka BP(1 ka¼ 1000 years before 1950 AD).

3.2. Carbon determination and mineral identification

For the carbon quantification 97 samples representing slices of1 cm were analysed for every 2 cm of core depth (Fig. 3). Totalcarbon (TC) was analysed with the LECO Truspec Macro elementalanalyser. Powdered samples of up to 150 mg were weighed into tinfoil and the encapsulated sample was dropped into the primaryfurnace (950 �C) and flushed with pure oxygen for combustion. Aninfrared detector measured the evolved CO2 for TC quantification.As calibration standard soils (LECO 502e309; 12.29� 0.37% carbon;LECO 502e308; 3.6� 0.29% carbon) were used (the RSD <2%).

The total inorganic carbon (TIC) content was determined withtheWoesthoff Carmhograph C16 analyser by evolving CO2 from theweighted (up to 200 mg) sample during mixing with hot (70 �C)acid (H3PO4) and subsequent quantification of the evolved CO2 in20 ml of a 0.05 N NaOH solution by conductivity. Calcite (CaCO3)was used as a calibration standard (12.01�0.14%; RSD <2%). Thetotal organic carbon (TOC) content was calculated by subtractingTIC from TC.

At 11 selected core depths qualitative and semi-quantitativemineralogical compounds were examined by X-ray powderdiffraction. Powdered samples were placed in the sample holderand analysed with the RIGAKU Miniflex600 instrument at 15 mA/40 kV (Cu ka) from 3� to 80� (2q) with a goniometer step size of



0.02� and a velocity of 0.5�/min. For the identification and semi-quantitative mineral composition analysis the software programX-Pert HighScore Version 1.0b by PHILIPS Analytical B.V. was used.

3.3. Palynological investigation

In total, 190 samples have been microscopically analysed forpollen and non-pollen palynomorphs (NPPs). Laboratory treatmentof the sediment samples, including pollen extraction and micro-scopic analysis, was performed at FU Berlin. Pollen and spores ofhigher plants and other NPPs were extracted from the samples(1.5 g wet sediment) according to standard procedures (Cwynaret al., 1979; Fægri et al., 1989), including 7-mm ultrasonic fine-sieving, HF (hydrofluoric acid) treatment and subsequent acetol-ysis. One tablet of Lycopodium marker spores, each containing18,584 spores (batch no. 177745), was added to every sedimentsample prior to the chemical treatment for calculating concentra-tions of identified palynomorphs (Stockmarr, 1971). Water-freeglycerol was used for sample storage and preparation of themicroscopic slides. Pollen and spores were identified at magnifi-cations of 400�, 600�, and 1000�, with the aid of published pollenkeys and atlases (Kupriyanova and Alyoshina, 1972, 1978; Bobrovet al., 1983; Reille, 1992, 1995, 1998; Beug, 2004) and a modernpollen reference collection stored at FU Berlin.

Preservation of extracted pollen and spores was generally good;corroded grains were rarely found. Bisaccate pollen grains of Pinusand Piceawere frequently broken, but easily identifiable. The pollenand spore content of the samples was sufficiently high to allow thecounting of a minimum of 300 terrestrial pollen grains per sample.In addition to pollen and vascular cryptogam spores, several otherpalynomorphs (NPPs) were identified and counted, including fungispores (e.g. Glomus, Thekaphora), algae colonies (e.g. Pediastrum,Botryococcus), and fragments of chironomid head capsulesfollowing van Geel et al. (1998). The chironomid analysis mayprovide valuable palaeoclimatic (e.g. warmest month air temper-ature) and palaeoenvironmental (e.g. lake water depth) informa-tion (e.g. Nazarova et al., 2013 and references therein), thoughprecise species identification requires special sample preparationand experience. Although detailed chironomid analysis of theKTK10 core sediment and chironomid-based reconstructions areplanned in the near future, these are beyond the scope of the cur-rent paper.

For all analysed fossil pollen samples, calculated pollen per-centages refer to the total sum of terrestrial pollen grains. For theother counted taxa, including pollen of aquatic plants, spores offerns and mosses, algae spores, chitin remains of non-biting midgeflies (chironomids) percentages were calculated using the totalterrestrial pollen sum plus the sum of palynomorphs in therespective group. The Tilia/Tilia-Graph/TGView software (Grimm,1993, 2004) was used for calculating pollen percentages anddrawing the pollen diagram (Fig. 4).

The biome reconstruction approach applied to the KTK1(Tarasov et al., 2009) and KTK2 pollen record (Bezrukova et al.,2010) from Lake Kotokel was also applied to the KTK10 LGM pol-len data set generated in this study. The principles of the methodwere first described in Prentice et al. (1996). Here, we applied twomodifications to the regional biomeetaxon matrix (Tarasov et al.,2009). Both successfully resembled the plant communities innortheastern Siberia for the last 50 ka (Müller et al., 2010). Thesemodifications affect the Betula sect. Nanae/Fruticosae and Alnusfruticosa (¼Duschekia fruticosa) taxa. Originally, both taxa wereattributed to the arctic and alpine dwarf shrub PFTs (plant func-tional types) and consistently used to distinguish the tundra biomefrom the boreal forest and cool steppe biomes (Tarasov et al., 1999).However, the morphology of birch pollen proves to be variable,


making it difficult to separate shrubby and tree taxa by means ofpollen analysis with a high degree of confidence. The problem canbe overcome by grouping all birch taxa into one broader category,e.g. Betula undiff. (e.g. Anderson et al., 2002), which then can beattributed to tundra and boreal/temperate forest biomes (Prenticeet al., 1996). According to the modified biomeetaxon matrix,Alnus fruticosa is attributed to both tundra and cold deciduousforest in line with work by Edwards et al. (2000) in northeasternSiberia.

4. Results

4.1. Sediment lithology and age determination

The analysed KTK10/6 core section (Fig. 2) consists of compacthomogenous dark-grey (greenish-dark-grey in the bottom part)slightly laminated silty clay (Fig. 2C). Light grey 1e2 mm thicklayers were noted between 14 and 21 cm, at 31, 35, 55, 75, 76, andbetween 174 and 183 cm depth. Two thin layers with non-identified plant fragments were registered at 168 and 180 cmdepth. Furthermore, non-identified insect fragments were found at9 and 156 cm depth, and non-identified plant remains were foundat 13,18, and 142 cm depth. The top and bottom quartiles containedfine sand particles, whereas coarse-grained sand was more abun-dant within the third quartile (94e141 cm; between ca. 24.7 and23.1 cal. ka BP). Ostracod shells and shell fragments were visuallyidentified along the whole analysed core segment, but were moreabundant within the uppermost 50 cm. The better-preservedostracod shells were collected and identified at FU Berlin. The re-sults are used to interpret the LGM environments.

The seven radiocarbon dates obtained on the samples from theanalysed segment of the KTK10 core vary from 17,230� 90 to21,780�110 14C years BP (Table 1). After calibration these datesyield calendar ages from ca. 20.7 to ca. 26 cal. ka BP (Table 1).Comparison of the high-resolution pollen record from the KTK10/6core (this study) with the coarse-resolution KTK2 pollen record(Bezrukova et al., 2010) using characteristic changes in theRanunculaceae pollen percentages (Fig. 2B) helps to correlate bothrecords (Fig. 2C) and to compare newly obtained radiocarbon dateswith the published KTK2 core chronology (Bezrukova et al., 2010).The graph combining KTK2 and KTK10/6 datasets (Fig. 2A) de-monstrates robustness of the published agemodel, which is used inthe current study. When applied to the analysed KTK10/6 record,the age model points to a very detailed sedimentary and environ-mental archive, which covers the LGM interval between ca. 26.8and 19.1 cal. ka BP (Fig. 2C) with a temporal resolution of ca. 32e58years (i.e. ca. 40 years on average). On the other hand, pollen-basedcorrelation (Fig. 2B) reveals very good correspondence for thelower and the middle Ranunculaceae peaks in the two records, butthe absence of the uppermost Ranunculaceae peak in the KTK2record. This may indicate that a ca. 3e7 cm thin layer (spanning ca.120e300 years) of the KTK2 sediment at the border between theKTK2/6 and KTK2/7 core segments (Fig. 2B) could not be recoveredduring the coring campaign. The KTK10/6 data generated in thisstudy allow this gap in the LGM record to be filled.

4.2. Carbon determination and mineralogical composition

The TOC content is relatively constant throughout the investi-gated core and values vary between 2.02 and 4.21%(median¼ 3.28%). The TIC values show a median of 0.71% and amaximum of 2.0% but minimum values �0.2% in the lowest part ofthe investigated section that are not reached elsewhere. Withrespect to the carbon analyses three different core sections (aec inFig. 3) were identified that are mainly reflected by changes in the


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ostracod shell fragments plant macro remains insect remains light grey lamina plant macro remains layer

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Fig. 2. (A) Ageedepth relationship for the KTK10 core segment, with newly obtained dates from the KTK10/6 core (squares) shown in relation to the KTK2 dates (circles) publishedin Bezrukova et al. (2010); (B) pollen-based correlation of the KTK2 and KTK10/6 sediments using relative percentage curves of Ranunculaceae pollen (0 cm in the KTK10/6 record isequivalent to 753.5 cm in the KTK2 record); and (C) the KTK10/6 lithology column (dark-grey slightly laminated silty clay) plotted against the age and depth scales.


TIC values. From ca. 26.8 to 25.8 cal. ka BP (core section a) the TIC islowest�0.2%whereas the TOC content shows relatively high valuesbetween 2.97 and 4.21%. After ca. 25.8 cal. ka BP (core section b) theTIC increases to a median of 0.78% and exhibits highest values (upto 2%) at ca. 22.7 cal. ka BP. The TOC content varies between 2.0 and4.1% (median 3.18%) and resembles that of core section a. After22.5 cal. ka BP (core section c) the TIC values decrease slightly(median 0.62% and the highest values around 1%) and once againthe TOC values vary between 2.5 and 4.18% as throughout the entirecore. Increased TIC values are often also accompanied by slightlyhigher TOC contents as shown in core sections b and c around23.9 cal. ka BP; 23.4 cal. ka BP; 22.7 cal. ka BP; 21.5 cal. ka BP and20.9 cal. ka BP.

The mineralogical composition is also very similar throughoutthe entire section and dominated by quartz (SiO2), plagioclasefeldspar (albite, NaAlSi3O8), alkali feldspar (orthoclase, KAlSi3O8)and the amphibole group. As phyllosilicates muscovite (KAl2(AlSi3)O10(OH)2), chlorite ((Mg,Fe)3(Si,Al)4O10(OH)2$(Mg,Fe)3(OH)6) andkaolinite (Al2Si2O5(OH)4) were identified. These minerals are pre-sent in all samples in nearly similar amounts as the different XRD-diagrams show only minimum differences. Calcite (CaCO3) is onlypresent in the XRD-diagrams after 25.8 cal. ka BP but then contin-uously occurs until 19.2 cal. ka BP.

4.3. Biological records

In total, 188 of 190 samples analysed for pollen and NPPs wereused to interpret the LGM environments. The two uppermost


samples showing high percentages of tree pollen, especially Pinussubgenus Diploxylon type, were excluded from the pollen data setand from further sedimentary analyses. An incursion of younger(and more fluid) sediment to the uppermost part of the samplerduring the coring operation was noted when the core was openedin the laboratory. We identified 60 pollen taxa, and 70 NPPs,including fern and fungi spores. The most characteristic taxa dis-tributions are summarised in a simplified percentage diagram(Fig. 4A).

Neither pollen spectra composition nor pollen-derived scores ofthe most characteristic regional biomes show any substantialchanges through the KTK10/6 record (Fig. 4B), thus suggestinggeneral stability of the vegetation cover during the analysed in-terval. The pollen assemblage representing the LGM interval can bedescribed as follows.

Herbaceous pollen taxa absolutely predominate in the analysedpollen spectra, whereas needleleaf coniferous tree/shrub taxa andbroadleaf deciduous tree/shrub taxa are sparse and do not exceedca. 2.4% and 5.4% (159.5 cm, ca. 25.8 cal. ka BP), respectively. Theshrub pollen sum contains mostly Betula sect. Nanae (0e3%), Alnusfruticosa (0e2%), and Salix pollen (0e1%). Pollen percentages ofEphedra and Ericales are low (0e1%) and restricted to the lower partof the KTK10/6 core section. Among herbaceous pollen taxa, Poa-ceae (grasses), Cyperaceae (sedges) and Artemisia (e.g. wormwood,sagebrush, etc.) are dominant with less abundant pollen of Aster-aceae subfamily Cichorioideae (up to 8%), Caryophyllaceae (up to6%), and Asteraceae subfamily Asteroideae (up to 6%). Ranuncula-ceae is constantly present in the pollen spectra, though its


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%

Fig. 3. Total inorganic carbon (TIC) and total organic carbon (TOC) contents from theKTK10/6 core plotted against the age scale.


percentages vary significantly throughout the record. ThreeRanunculaceae percentage maxima were identified in the lowerand middle part of the core, including a less pronounced one (up to13% at ca. 25.5 cal. ka BP), followed by a second maximum (up to28%) at ca. 23.4 cal. ka BP and a third maximum (up to 18%) at ca.22.3 cal. ka BP. Pollen concentrations vary fromw4750 grains/gramto w51,000 grains/gram, averaging ca. 16,000 grains/gram.

Monolete spores of Polypodiaceae ferns are continuously pre-sent with relatively low values (less than 2%) throughout the wholerecord, followed by less frequent trilete spores of Botrychium(moonworts) and even more occasional Lycopodiaceae (club-mosses), including Lycopodium annotinum, L. clavatum type, andHuperzia selago type (Fig. 4A).

Spores of Glomus, an endomycorrhizal fungus that forms sym-biotic relationships (mycorrhizas) with plant roots, are very abun-dant especially in the middle part of the core (to 11% at ca.22.1 cal. ka BP), whereas its percentages generally do not exceed 3e4% in the most part of the record. Spore balls of the smut fungus(Thekaphora) which is a plant-parasitic microfungus reproducing invarious organs of the host plants (Vanky et al., 2008) are quasi-continuously found throughout the record, though in low per-centages. Spores ofDelitschia, a coprophilous fungus, andmycelia ofGeumannomyces, a pathogen mainly on Carex species, have beenfound in a few samples (Fig. 4A). Conifer tracheids, elongated cellsin the xylem of vascular plants that serve to transport water andminerals, are found in nine samples along the analysed record(Fig. 4A).

Pediastrum algae colonies are highly abundant, with values up to88% at around 22.6 cal. ka BP, the highest values being concentratedin the middle part of the record between ca. 24 and 22.5 cal. ka BP.Botryococcus colonies reach levels up to 38%; however, the highestvalues occur between 22.5 and 19.5 cal. ka BP, with a distinctdecrease in percentages between ca. 25 and 23 cal. ka BP. The


resting algae cells of the Zygnemataceae family, including Spirogyrasp., are present throughout the whole sequence, but in very lowpercentages.

Ostracod shells were rarely intact, thus hampering identificationof specimens. Nevertheless, Cytherissa lacustris and valve remainsof the subfamily Candoninae show almost continuous presencethroughout the KTK10/6 record.

Numerous fragments of chironomid larval head capsules arefound in the analysed samples in remarkably high quantities(Fig. 4A). The sample from 83 cm (ca. 22.78 cal. ka BP) depth revealshead capsules of the Sergentia coracina type. Moss remains arerecognized at 168 (ca. 25.53 cal. ka BP) and 180 cm levels (ca.26.23 cal. ka BP). However, poor preservation hindered more pre-cise identification.

5. Interpretation and discussion

5.1. The LGM vegetation and environments

The KTK10/6 pollen record spans the time from ca. 26.8 to19.1 cal. ka BP, thus covering the whole interval conventionallyassigned to the LGM (e.g. Clark et al., 2009). The LGM pollen spectracomposition and taxa percentages reflect regional and local vege-tation composition around Lake Kotokel. Previous studies innorthern Eurasia (e.g. Prentice et al., 2000) and in the Lake Baikalregion (Tarasov et al., 2005, 2009; Bezrukova et al., 2010) demon-strated that the main regional vegetation types (or biomes) can bereliably reconstructed by applying the biomisation approach(Prentice et al., 1996) to the late Quaternary pollen records. Thepollen-based biome reconstruction (Fig. 4B) demonstrates thehighest scores for steppe (ca. 20) followed by tundra (ca. 12), sug-gesting that herbaceous tundra and steppe vegetation predomi-nated in the region owing to the substantially colder than presentregional climate. High percentages of Artemisia, Poaceae, Cyper-aceae (up to 90% of total pollen sum) and a rich variety of otherherbaceous taxa point to a rather productive vegetation. Very lowpercentages of boreal tree and shrub pollen and consequently verylow scores of the cold deciduous forest biome (0e3.3) throughoutthe whole record support the reconstruction of the open regionalvegetation in line with generally colder and drier than presentclimate conditions. However, the existence of a permanent lake andthe low pollen percentages of the taxa indicators of dry environ-ments in Inner Asia (e.g. Chenopodiaceae and Ephedra) do notsuggest semi-desert or desert vegetation and a correspondingclimate in the region during the LGM.

Our current results confirm the reconstruction of cold steppeand herbaceous tundra communities with minimal representationof woody taxa in the regional vegetation ca. 28e18 cal. ka BP basedon the coarse-resolution KTK2 pollen record from Lake Kotokel(Bezrukova et al., 2010). Furthermore, the KTK2 and KTK10 LGMpollen assemblage composition, taxa diversity and relatively highpollen concentrations do not support the viewpoint of some au-thors (e.g. Ray and Adams, 2001) who suggested polar and alpinedesert environments with less than 2% of the ground covered byvascular plants around Lake Baikal and in major parts of northernAsia during the LGM interval. The pollen concentrations in thesurface samples from the Siberian tundra north of Lake Baikalusually do not exceed 1000e2000 grains/gram (Müller et al., 2010),whereas values calculated for the KTK10/6 sediment are substan-tially higher. Available pollen (Anderson et al., 2002; Müller et al.,2010; Andreev et al., 2011; Lozhkin and Anderson, 2011) andplant macrofossil (Kienast et al., 2005) records of the LGM intervalobtained from more northern regions of eastern Siberia also indi-cate that productive meadow and steppe communities played animportant role in the Siberian vegetation during the last glacial


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Please cite this article in press as: Müller, S., et al., Stable vegetation and environmental conditions during the Last Glacial Maximum: Newresults from Lake Kotokel (Lake Baikal region, southern Siberia, Russia), Quaternary International (2013), http://dx.doi.org/10.1016/j.quaint.2013.12.012


interval and served as food resources for large populations of her-bivores (Kienast et al., 2005).

The KTK10/6 pollen spectra composition resembles (although ata less precise taxonomic level) the LGM plant macrofossil assem-blages’ composition from the “Mamontovy Khayata” permafrostsequence (71�600N, 129�250E) on the Bykovsky Peninsula, whichwas interpreted as similar to modern vegetation mosaics of theYakutian relict steppe (Kienast et al., 2005). In contrast to the LGMrecords from northern Yakutia (Andreev et al., 2002; Kienast et al.,2005; Müller et al., 2010; Lozhkin and Anderson, 2013) showinghigh concentrations of Selaginella rupestris (rock spike-moss)spores, the Lake Kotokel record reveals only a sporadic appear-ance of this taxon e an indicator of disturbed and dry soils or drysparsely vegetated rocky environments (Andreev et al., 2002). Suchregional differences in the floristic composition of the LGM vege-tation likely indicate less continental and less arid environments inthe southern part of eastern Siberia compared to the central andnorthern regions.

Crowley (1995) reconstructed a conifer forest belt across west-ern and central Siberia within 55e60�N during the LGM, and LGMvegetationmaps compiled by Grichuk (Grichuk, 1984; Frenzel et al.,1992) show cold boreal conifer and deciduous trees in southernSiberia (e.g. in the Altai Mountains and around Lake Baikal), sug-gesting many scattered refugia from which tree vegetation couldquickly spread as climates warmed. Although low percentages ofarboreal pollen recorded in the LGM sediment from Lake Kotokel(Fig. 4A) do not support a continuous boreal forest belt, the totaldisappearance of cold/drought-tolerant boreal trees and shrubsfrom the regional vegetation cover is unlikely. Conifer tracheids andstomata are identified in the pollen spectra; together with borealconifer and broadleaf tree and shrub taxa pollen occurringthroughout the KTK10/6 record (Fig. 4A), they suggest the presenceof single trees or small forest stands in the lake vicinity, likely in thestream valleys. A similar conclusion that small populations ofboreal trees and shrubs were capable of surviving long periods ofthe harsh climate at the LGM in the Asianmid-latitudes appeared inthe most recent syntheses and re-analyses of the available pollenand archaeological charcoal data (Vasil’ev et al., 2002; Brubakeret al., 2005; Tarasov et al., 2007; Williams et al., 2011).

The pollen-based reconstruction of vegetation (Müller et al.,2010) and climate (Tarasov et al., 2013b) from Lake Billyakh(65�170N, 126�470E, 340 m a.s.l.) in the western central part of theVerkhoyansk Mountains suggests a mean July temperature ofapproximately 8e10 �C and mean annual precipitation of about270 mm, confirming the cool grass/shrub vegetation around LakeBillyakh during the coldest and driest phase of the last glacialbetween ca. 32 and ca. 15 cal. ka BP. However, modern larch dis-tribution patterns from arctic Siberia north of Lake Billyakhdemonstrate that individual larch plants can survive within ashrub and grass tundra landscape even under mean July temper-atures of about 8 �C (Pisaric et al., 2001). It is unlikely that lastglacial environments around Lake Kotokel located about 1700 kmsouth-west of Lake Billyakh, were as cold as in central Yakutia.Therefore, lower-than-present atmospheric precipitation andmoisture availability could have been a main limiting factor fortree growth there. Comparing the LGM pollen spectra of the KTK2core with the pollen assemblages and pollen-based climate re-constructions derived from the CON01-603-2 sediment core fromLake Baikal (Tarasov et al., 2005), Shichi et al. (2009) estimated anannual precipitation of less than 250 mm and a mean Januarytemperature dropping down to �32 �C during the LGM period.Although this interpretation by Shichi et al. (2009) can only beregarded as very preliminary and requires further proof, it de-monstrates general cooling and drying of the LGM climate in theLake Baikal region.


The regional pollen/vegetation-based interpretation of the LGMclimate is further supported by other evidence from the KTK10/6sediment. Thus, the ostracod species Cytherissa lacustris and thechironomid species Sergentia coracina are generally cold-adaptedtaxa (Nazarova et al., 2013) that recently occur most abundantlyin the profundal zone of oligo- to mesotrophic freshwater lakes(Hofmann, 1971; Meisch, 2000). But during colder climatic phasesthey also occur in shallow lakes (Hofmann, 1971; Kossler, 2010);especially Cytherissa lacustris benefits from a higher content ofdissolved oxygen in colder lake waters. According to Antonssonet al. (2006), the chironomid S. coracina has its optimum at meanJuly temperatures of 13 �C. This value matches the climatic inter-pretation of the LGM pollen spectra from Lake Kotokel (Shichi et al.,2009) and the quantitative reconstruction of glacial climate aroundLake Baikal (Tarasov et al., 2005). Mesotrophic water conditions aresupported by the NPP record (e.g. Type 187B: van Geel et al., 1998),as well as by the identified algae taxa abundant in the eu- tomesotrophic freshwater shallow lakes, quickly warming up duringthe summer (van Geel et al., 1998; Miola et al., 2006). Plant ma-crofossils, e.g. decomposed moss remains, found in the core sedi-ment likely indicate a lower-than-present surface of the LGM lake,and closer location of the KTK10 coring site to the LGM shoreline inresponse to the drier-than-present climate. Peaks in Ranunculaceaepollen could be also interpreted as an indicator of the littoral zoneand/or meadow vegetation communities close to the KTK10 site,particularly between ca. 26 and 22 cal. ka BP. The slightly increasedTIC values between 25.8 and 22.5 cal. ka BP likely representenhanced calcite production during summer when a decreasedwater volume becomes additionally warmer and productivity isenhanced as shown by often associated higher TOC and TIC con-tents. Littoral pioneer vegetation communities, with Ranuncula-ceae species occupying erosive soils in the range of fluctuatingwater levels at shores of shallow lakes and regularly inundateddepressions (Hilbig, 1995; Dierßen and Dierßen, 1996), were acharacteristic part of the LGM vegetation mosaic in eastern Siberia(Kienast et al., 2005). The presence of sand in the KTK10/6 sedimentsupports intensified soil erosion and/or proximity to the coastalzone, whereas the increase in coarse-grained sand particles in theinterval between ca. 24.7 and 23.1 cal. ka BP parallels the generalincrease in Ranunculaceae pollen percentages. Relatively highpercentages of Glomus might also point to intensified soil erosion.In the European records, spores of this fungus, which occurs in avariety of host plants, including a number of herbaceous plantfamilies, are reported to be especially abundant in late glacial en-vironments with highly eroded soils (van Geel et al., 1998).

As pollen analysis does not allow robust assignment of Ranun-culaceae pollen grains to the species (or even genus) level, anumber of interpretations involving various representatives of theRanunculaceae family native to marshes, fens and wetlands andflourishing in a landscape inundated with snowmelt waters (e.g.Caltha palustris, Ranunculus reptans) can be suggested. However, allscenarios agree well with the smaller size of the lake and proximityof the coring site to the lake shore during the LGM. Furthermore,our interpretation of a lower lake level prior to 15 cal. ka BP isindependently supported by the recent bathymetric and geophys-ical studies at Lake Kotokel, reporting traces of two former riverchannels along the northeastern coast, ca. 10 m below the presentlake level (Zhang et al., 2013).

Published faunal records from the study region also provideevidence for continental and cold LGM climate and open drysteppe, tundra-steppe and meadow-steppe vegetation, in line withthe available plant and sedimentary records. The faunal remains ofthe last glacial interval are known from a number of archaeologicaland cave sites as well as from several natural open sections(Erbajeva et al., 2011) and show that the distribution areas of some



steppe dwellers such as Marmota sibirica (Tarbagan marmot),Ochotona daurica (pika) and Lasiopodomys brandti (steppe vole)were extended far beyond their present-day ranges in Mongoliatowards the north (Erbajeva et al., 2011).

5.2. The LGM environments and humans

Strengthening and correcting the earlier interpretations of theLGM environments in the Baikal region based on various butdiscontinuous proxy records (e.g. Chlachula, 2001 and referencestherein), the KTK10/6 sediment provides a robustly dated andcontinuous environmental archive of the interval between ca. 26.8and 19.1 cal. ka BP. This environmental archive of decadal-resolution demonstrates a general stability of the LGM vegetationin the Lake Kotokel region and most probably in the greater areaaround Lake Baikal. Additionally, sedimentological parameters suchas TOC contents and mineralogical composition show that thelimnic conditions within Lake Kotokel remained relatively stablethroughout this period. Solely the slightly increased TIC contents eoften accompanied by higher TOC values e reflect changes towardsdecreased water volume and higher biological productivity. High-resolution climate reconstruction gained from the Greenland icecores demonstrates significant temperature oscillations with amagnitude of up to 7e11.3 �C during the LGM interval at about 27e19 cal. ka BP (Alley, 2000, 2004). The Antarctic EPICA Dome C recordalso demonstrates frequent temperature oscillations during thisinterval (Jouzel et al., 2007), though of much smaller magnitude(i.e. 1e2.7 �C), suggesting large differences in temperature changesin the North Atlantic and more distant regions. Results of thepalynological investigation presented in this paper (Fig. 4A) shownumerous decadal/century/millennial scale oscillations in the taxapercentages, which likely reflect respective oscillations of theglobal and regional climate. However, as indicated by the relativelysmall changes in the calculated biome scores (Fig. 4B), these cli-matic fluctuations were obviously not powerful enough to desta-bilise the predominance of the cool steppe vegetation in the region.

Results of the geoarchaeological research conducted in theMediterranean region suggest that extreme oscillations towards acold/dry climate (e.g. Bartov et al., 2003), most pronounced in andaround the North Atlantic region (Alley, 2004), led to a majorreduction of the potential living area and the collapse of humanpopulations there during the coldest phases of the last glacial in-terval (Davies et al., 2003a, 2003b; Weniger, 2008 and referencestherein). More recently, Schmidt et al. (2012) published a majorstudy, based on the extensive number of 152 archaeological cavesites and rock shelters, analysing the environmental impact ofNorth Atlantic Heinrich Events (HE) on the human population onthe Iberian Peninsula. Their conclusion is that “climatic deteriora-tion during the different HE repeatedly lead to a near-completebreakdown of settlement patterns, but following each HE therewas a major reorganisation in settlement patterns on the IberianPeninsula” (Schmidt et al., 2012: 179). By contrast, the Lake Kotokelrecord presented in the current paper shows no noticeable changein the terrestrial pollen taxa composition (Fig. 4A) nor in the pollen-derived biome scores (Fig. 4B) even during the HE2, one of thecoldest episodes of the last glacial, dated to ca. 24 cal. ka BP andwell pronounced in the d18O records from Greenland (Svenssonet al., 2008) and from Chinese stalagmites (Wang et al., 2001).

The growing body of archaeological data on the Late Palaeolithichabitation of southern Siberia and the Baikal region shows a rela-tively high number of sites with radiocarbon dates in the range of25e17 ka BP (i.e. ca. 28e18.3 cal. ka BP), suggesting that environ-mental stress associated within the LGM interval did not causeserious difficulties to the local human population, as it did in thewestern regions of Eurasia (Dolukhanov et al., 2002). In an attempt


to explain this phenomenon, Dolukhanov et al. (2002) employedquantitative estimates of the LGM climate (Tarasov et al., 1999),which supported productive steppe plant communities and indi-cated very thin snow cover in central Siberia. Hence, the dry grassfodder was easily available beneath the thin snow cover and couldsupport large herds of herbivores, which in turn were effectivelyexploited by the Palaeolithic hunter-gatherers (Velichko andKurenkova, 1990). Bones of the large herbivores such as horse,woolly rhinoceros, woollymammoth, bison, red deer, roe deer, wildsheep andMongolian gazelle are reported in the archaeological andgeological records dated to the LGM in the Baikal region (Kuzmin,2009; Lbova, 2009 and references therein).

A further argument against the considerable (or even complete)depopulation of Siberia during the LGM (e.g. Goebel, 2002)emerged as a result of a rigorous analysis of 437 radiocarbon datesfrom the Middle and Upper Palaeolithic archaeological sites(Kuzmin and Keates, 2005). Their analysis suggests that e in termsof the relative size of the Siberian Palaeolithic population based onthe frequency of occupation episodes e population density wassmall until ca. 36 ka BP, and subsequently increased gradually fromca. 36 to 16 ka BP (ca. 41.3e19.1 cal. ka BP). Comparison of calibrated14C dates from Siberian archaeological sites with Greenland ice corerecords performed by Fiedel and Kuzmin (2007) does not demon-strate an easy correlation between the North Atlantic-centred cli-matic fluctuations and the human occupation dynamics in Siberiabetween ca. 36 and 12 cal. ka BP and does not indicate that coldclimate created significant challenges to humans in Siberia duringthe LGM.

6. Conclusions

The present study demonstrates the high potential of the KTK10core sediment recovered from Lake Kotokel in 2010 for (i) gaininghigh-resolution palaeoenvironmental data from this region ofsouthern Siberia and for (ii) verifying earlier published hypothesesbased on the discontinuous, low resolution and/or poorly datedarchaeological and sedimentary archives. The sedimentary datafrom the KTK10/6 section presented here covers the time intervalbetween ca. 26.8 and 19.1 cal. ka BP conventionally termed as theLast Glacial Maximum at an average temporal resolution of ca. 40years. It reveals the regional vegetation composition and local lakeecosystem history during the LGM. Furthermore, the KTK10/6pollen record correlated with the KTK2 sediment proves thediscontinuity of the previously published coarse-resolution LGMrecords and helps to fill this identified gap.

The results of pollen analysis and pollen-based biome recon-struction show that steppe and tundra communities composed ofgrasses and various herbs predominated in the regional vegetationcover between ca. 26.8 and 19.1 cal. ka BP. Occurrence of conifertracheids and stomata throughout the KTK10/6 record, togetherwith small quantities of boreal conifer and broadleaf tree and shrubtaxa pollen, reflects the presence of single trees or small groups oftrees close to the lake, most likely in the river valleys or in thelocally moist environments. Numerical scores of the most charac-teristic biomes (steppe, tundra and cold deciduous forest) showminor fluctuations, signifying stability of the regional vegetationcover during the whole analysed time interval.

Continuous lacustrine sedimentation, little changes in sedi-mentological parameters and generally low contents of droughtindicator taxa revealed by the KTK10/6 record do not supportpronounced aridity of the LGM climate in the study region, thoughconditions were drier and colder than at present.

In contrast to the stable regional vegetation cover and sedi-mentological conditions in Lake Kotokel, greater sensitivity todecadal- and century-scale climate variability is seen in the isotopic



records from the ice cores and cave stalagmites. The Ranunculaceaepeaks in the pollen record reflect decreases in the lake surface areaand expansion of the littoral and meadow vegetation communitiestowards the coring site. The highest pollen percentages of Ranun-culaceae registered at ca. 23.8e23.4 cal. ka BP, together with anincrease in coarse-grained sand particles in the KTK10/6 sediment,likely represent the lowest lake stand of the whole record.

Published geoarchaeological data from the Mediterranean re-gion suggest that major oscillations towards cold and dry climateduring the last glacial could be a reason for a noticeable depopu-lation of this region. On the contrary, the archaeological andzooarchaeological data from the Palaeolithic sites in southernSiberia demonstrate that the cold climate did not create significantchallenges to humans during the LGM. A general stability of thegrassland vegetation and lake ecosystem in the study region ca.26.8e19.1 cal. ka BP, inferred from the high-resolution KTK10/6sedimentary record, supports the hypothesis that this productivelandscape could stably serve as a perennial food resource for largepopulations of herbivores and provide favourable environments forthe local hunter-gatherers inhabiting the Lake Baikal region duringthe LGM interval.

Acknowledgements

This work is a contribution to the “Bridging Eurasia” researchprogramme initiated during the International Workshop at FUBerlin (April 28eMay 2, 2010) sponsored by the Russian Foundationfor Basic Research (RFBR), German Research Foundation (DFG) andGerman Archaeological Institute. The authors acknowledge finan-cial support from the DFG (TA 540/4, TA 540/5 and MU 3181/1), theRFBR (12-05-00476a) and FU Berlin (Innovation Fund). We aregrateful to A. Shchetnikov, E. Ivanov, E. Dobretsov and O. Levina fortheir active participation in the coring campaign on Lake Kotokel inJuly 2010 and to Prof. F. Riedel for providing additional financialsupport for three AMS dates. We sincerely thank A. Beck (FU Berlin)for English proof reading and two anonymous reviewers for helpfuland constructive comments to an earlier version of this manuscript.

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Stable vegetation and environmental conditions during the Last Glacial Maximum: New results from Lake Kotokel (Lake Baikal region, southern Siberia, Russia)